Evolutionary Psychology & How It Affects Sleep (Part 2)

Survival of the fittest. Natural selection. Evolutionary psychology. Perhaps it seems odd to associate these Darwinian-based terms with sleep. Yet, from an evolutionary standpoint, sleep is one primitive behavior that has become firmly rooted in our human experience.

In Part 1 of our 2 part blog series, we covered the basics of human evolution and illustrated why evolutionary psychologists believe that our brains still operate with the mentality of our Stone Age ancestors. This article will take a look at why–with all of our evolutionary advancements–humans still sleep for a duration equating to ⅓ of their total life.

Sleep & Evolution

Sleep has endured through all forms of natural selection and the evolutionary process. Through environmental selection, the weakest of the species die off–their shortened life span doesn’t allow them enough time to pass along their genes. Sexual selection, however, infers that by appearing as weak, these members of the human race become unattractive to others. Yet, in all of the scenarios of natural selection, we as humans have undergone little evolutionary development in the last few hundred centuries, and it seems that sleep is one characteristic trait deeply tied to our survival.

If you think of our Stone Age ancestors, you’d wonder how sleep could be linked to greater chances of survival. With danger lurking, how could lying unconscious and motionless for a third of our lifetime be linked to an increased chance of survival?

“Contrary to first impressions, animals may sometimes be less vulnerable to attack by predators while asleep. When an animal is awake and maneuvering in its environment, it can forage for food, eat and mate, but it will also expend energy by engaging in such behaviors and can wander into harm’s way. Most likely sleep evolved to ensure that species are not active when they are most vulnerable to predation and when their food supply is scarce. Although slumber seems to serve many roles, sleep patterns across species may enhance survival by optimizing the timing of activity and idleness while also allowing us to maintain the most agile brains.”

Effectively, sleep has endured through the entire history of the Homo sapiens population due to its innate ability to enhance our survival rates along with our quality of life. During sleep our glymphatic system washes away organic materials and proteins as a nightly detoxification, our memories from the day are processed and stored, we reset our creativity, restart our minds, and awaken each morning to new and exciting possibilities. Though one can only estimate at the full scope of these sleep-derived evolutionary benefits, it can be said that sleep must be hugely important to our health, wellness, and wellbeing for it to survive throughout more than 100,000 generations of humankind!

Food for thought: If sleep is this vitally important to our survival as a species, perhaps it’s time that you consciously prioritize sleep in your own life.

How has prioritizing sleep changed how you interact with the outside world?